Gold Nanoparticles inside Bacterium (IMAGE) University of California - Berkeley Caption A single nanocluster of 22 gold atoms -- Au22 -- is only 1 nanometer in diameter, allowing it to easily slip through the bacterial cell wall. Credit Peidong Yang, UC Berkeley Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.